Document U.S. Pat. No. 6,285,773 (Carme) discloses an active noise rejection system, comprising one or several linear loudspeakers arranged at the edge of a double glazing, in the air layer between the two glass panes and/or inside a framing profile of this double glazing. In this noise rejection system, the loudspeaker makes it possible to realize an electro-acoustic system that is practically invisible, and which is not detrimental to visual comfort or to the light transmission of the glazing, with the proposed system making it possible to improve the sound insulation of a double glazing in particular in the low frequencies.
The loudspeaker described in the Carme patent, comprises a vibrating membrane disposed between two adjacent glass panes in such a way as to vibrate and generate a counter-noise in the air layer. This membrane is associated with an actuator suitable for inducing a vibratory movement to said membrane. A control electronics makes it possible to control the actuator according to the acoustic signals sensed by at least one control microphone carried by the frame of the window. The Carme patent does not focus however on the position that the control microphone has to have in order to optimize the filtration of the noise.
Patent document EP 0.710.946 (CENTRE SCIENTIFIQUE ET TECHNIQUE DU BATIMENT) also relates to a multi-glazed window incorporating an active noise reduction device. In this document, it is taught to position control microphones in the middle of the air layer, at equal distances from the two glass panes, in the longitudinal median plane of the window. The results obtained in terms of noise attenuation are however not optimal. Furthermore, the attenuation is effective only in a narrow frequency band corresponding to the low frequencies.
Patent document CN 201.620.733 (XINMIN) also discloses an active noise reduction system comprising a loudspeaker arranged in a triple glazing, in the air layer separating two glass panes. The loudspeaker and the control microphone are in the same plane.
The invention aims to overcome this situation. In particular, an objective of the invention is to improve the attenuation of the noise in a multi-glazed window of the type known from prior art mentioned hereinabove.
Another objective of the invention is to obtain an attenuation of the noise in a wide frequency band.